Developer API

UTCTime exposes a free, public REST API. No authentication, no API key, no rate-limit headers to negotiate in normal use. All endpoints are served from Cloudflare's global edge network and return application/json.

Machine-readable spec: openapi.json (OpenAPI 3.0). For agent use: llms.txt.

Base URL

https://utctime.date

Versioning

The API is currently unversioned (v1, stable). Breaking changes will be introduced under a /api/v2/ prefix with at least 90 days notice in llms.txt and a Deprecation response header on the old endpoints. Additive changes (new fields, new optional parameters) are not considered breaking and may be made at any time.

Rate limits

60 requests per 10-second window per IP. On a 429 the response includes Retry-After: 10. Standard use never comes close to this limit.

Endpoints

GET /api/convert

Convert a time between two IANA time zones.

Parameter	Required	Description
`from`	yes	Source IANA zone, e.g. `America/New_York`
`to`	yes	Target IANA zone, e.g. `Europe/London`
`time`	no	ISO 8601 timestamp. Defaults to now.

curl "https://utctime.date/api/convert?from=America/New_York&to=Europe/London"

GET /api/now

Current time in a specific zone.

Parameter	Required	Description
`zone`	yes	IANA timezone, e.g. `Asia/Tokyo`

curl "https://utctime.date/api/now?zone=Asia/Tokyo"

GET /api/overlap

Find UTC hours where all supplied zones share working hours (09:00–17:00 local).

Parameter	Required	Description
`zones`	yes	Comma-separated IANA zones (min 2)
`date`	no	YYYY-MM-DD. Defaults to today.

curl "https://utctime.date/api/overlap?zones=America/New_York,Europe/London,Asia/Tokyo"

GET /api/zones

List all supported IANA time zone identifiers. Cached for 7 days.

curl "https://utctime.date/api/zones"

Error responses

All errors return JSON with an error field and the appropriate HTTP status code:

{ "error": "from and to zone required" }  // 400
{ "error": "invalid timezone" }           // 400
{ "error": "rate limited" }               // 429

When to use this API

Use the UTCTime API when you need to:

Convert a specific timestamp between two time zones (DST-aware)
Find the current local time in any IANA-named zone
Compute overlapping business hours for a distributed team
Enumerate all IANA time zone identifiers supported at runtime

You do not need this API to: display a static UTC clock (use Date in JS), or handle user-local time only (use the browser's Intl API directly).

Questions

[email protected]